Voltage regulating transformer



Sept. 15, 1959 J. E. M CLAIN VOLTAGE REGULATING TRANSFORMER 2Sheets-Sheet 2 Filed June 20, 1956 R mw m0 V WM 5 c. e m u ATTOE/VE)United States Patent 2904;743 voilracn neeutnave James E.=- McClain;Grenville, Tex. Ap siieaaan Ju'iie 20-, 1956, Serial No. 5925-37"zclaims or.- m ss This" invention relates to an electric current trans"-fofnier and has for its principal o 'ct to provide a vhlta'ge regulatingtransformer and circuits therefor toriiain tain an output current havinga constantly uai fornr volt age regardless of fluctuation in voltage ofthe input current.

Other objects of the invention are to provide transformer mechanismsforuse as a satin variable voltage seu'r'ce; an automaticseir-voitage-ie nlator", a constant current tr nsformer; I

A further object of the invention is to pfovide a transformer with meansfor controlling the voltage of the secondar current responsive to acontrol of saturation in the core portion of the transformer whichcarries the secefi dar'y winding.- 7

t is also an object of the invention to provide a trans fo' hier wher'inthe voltage ofth'e outputcurrent may he stepped 1115i or" down andmaintained sutssfanfiauy Cons'tant for the new value.

v A further object of the inventionis to provide a transformer mechanismwhich functionsas a' magnetic amplifier in produc'ing'direct currents ofvery large magnitude relatively to the initial alternatingcurrentsupplied to the transformer mechanism. a

In accomplishing these and other objects of the invention as hereinafterpointed out, I have provided improvedstructure, the preferred forms ofwhich are illustrated in the accompanying drawings, wherein: X

Fig". lis a side elevationalview of the basic core and coil arrangementof a transformer embodying the featur'es of the present invention forproducing an alterr'i'ating 'curfent of constant uniformvoltage with aninput current ofvariable voltage. V v I ig'. 2; is a diagrammatic viewof the voltage regulating ciicuit in whichthe transformer is connectedfor maintaining automatically any predetermined output voltager Fig. isa' diagrammatic view of a circuit for automatically maintaining anoutput currefit having aconstantly uniform voltage. v

Fig. 4 is a perspective view of. the transformer. N

Fig. is a diagrammatic view of. the transformer in a circuit forproducing direct currents of relatively large magnitude. 7 v

Referring more in detail to the drawings:

1 designates the Basic transformer for converting an alternating currentfrom an established primary source an induced secondary current ofdffferent value but having a constantly uniform voltage. a Thetransformer 1 includes a core 2 composed of preferably silic'onsteellaminations and shaped to provide parallel -leg portions 3 4 and 5. Theleg portions- 3, 4' and 5 are connected at their respective ends by barportions 6 and 7 to form c'ls'ed magnetic circuits. The leg portion 3carries a ary winding 8 having terminals and it) for connecjftablished'sour'c'e of primary current which ting" voltage, for eras na-high tentransmission system. may earned on partisan-1's seeefiaaiwining" 1t and when sio the leg 2,904,743. Patented Sept. 15, 1.959.

has a number for turns relatively to the turns of. the p'rig marywinding to give an induced alternating current at the terminals 12 and13 which has a voltage of desired magnitude such as may be safely usedto supply, for example, a house circuit. It is to he understood,liowever, that the purpose of the transformer is for explanatorypurposes only, and thatthe invention. is adapted't'o transformers ofvarious input and output capacities.

When the input current fiows in' the primary winding 8 amagnetic fieldis set up in the coil tomagnetize the core first in one direction andthen in the other to set. up

a magnetic induction or flux which produces an alter natingelcctromotive force or current in the secondary winding 11. V H V Thefunction of the current flow in the primary windi-ng and the inducedflow in the secondary winding as thus far described is in accordancewith any conventional transformer and any change in voltage of the inputcurrent to the primary Winding results in a corresponding fluctuation inthe voltage of the output current from the secondary Winding, with theresult that the various appliances that may be connected in the housecircuit do notoperate efiiciently or in accordance with their ratedcapacities. The fluctuation in voltage of the output current is'causedby variation of the magnetizing force which results from the primarycurrent, which in turn results in variation of the magnetic induction orflux that generates the secondary current in the secondary winding ofthe transformer. In overcoming this difficulty the present invention;contemplates-an inversely variable. mag: netic force which is inducedinto the core of the transformer for maintaining a balanced magneticinduction or flux regardless of variation in the voltage of the inputcurrent. By maintaining a balanced or uniform flux in the core of thetransformer, an output current of constantly uniform voltage isgenerated in the secondary windingof the transformer. In obtaining thisresult, the secondary winding 11 is placed at one end of the leg portion4 of the core and an opening 14 is provided through the opposite end ofthe leg portion and immediately ad-- jacent its connection with the barportion 6. The opening through the leg portion 4 thus provides branchlegs 15 and 16. Mounted on thebranch leg portions 15 and 16 areoppositely wound coils 17 and 18, respectively, having the ends adjacentthe secondary winding intercom nected as indicated at 19 and-theiropposite ends con nected with terminals 20 and 21 for connection with adirect current which fluctuates in accordance with fluctuation of theinput current. The coils 1-7 and 18 are thus connected in series forflow ofthe' direct current there-' through inacontinuous direction.However, since the coils I7 and 18 are wound in opposite directions theinduced alternating current generated therein is of opposite polaritywith the result that the fundamental frequency component of thealternating current at the terminals 2% and 21 is zero and only themagnetism induced lry the direct current is utilized in effectingsaturation of the branch portions of the leg 4. a

The leg portion 5' of the transformer is similar to the leg portion 4 inthatit is also provided with an opening; 22. to provide branches 23 and24 at theend immediately adjacent the bar 6.-- Mounted on the branches23 and 24 v are coils: 25 and 26 which are wound reversely to each"other and connected together atone end as indicated at- 27 with theiropposite ends-connected to terminals 28 and 29 in that no alternatingcurrent component of fundamental frequency can flow through these coils:The poil 18 on the branch 16 of the leg 4 also has a small alter natingcurrent winding 30 concentric therewith to provide an alternatingcurrent that is rectified for supplying a direcfuffent voltage to thecoils 25 and 25 on branches 23 and 24 of the leg portion 5, which cumint g 3 produces a magnetic force which is inverse in intensity to thatgenerated by the coils 17 and 18.

Fig. 2 shows one form of circuit which includes the transformer 1 asjust described, wherein a manually operated auto transformer 31 can beused for supplying a variable direct current to the coils 17 and 18 insuch fashion that the current in the secondary winding 11 may go fromzero value to full value depending upon the setting of an autotransformer 31. The induced alternating current in the winding of theauto transformer is used to supply a direct current to the coils 17 and13. his is effected by connecting one of the terminals, for example, theterminal 20, with one terminal of a current rectifier 33 and the otherterminal 21 with the primary supply. The movable contact element 34 ofthe rheostat is connected with the opposite terminal of the rectifierwhereby the primary current is rectified and a correspondingly variablevoltage direct current is supplied to the terminals 20 and 21 of thecoils 17 and 18.

The induced current in the coil 3i) is converted to a direct current bymeans of a rectifier 35 that is connected with the movable element 36 ofa rheostat 37, one end of which is connected to one terminal of the coil3%, the other terminal of the coil 3t) being connected with therectifier 35.

The method used to maintain a constant voltage of the output currentacross the terminals 12 and 15 of the secondary winding with a variableinput voltage across the terminals 19 and 9 of the primary winding 8 isas follows for a flat compound automatic operation with the transformerconnected as an auto voltage regulator as shown in Fig. 2.

For example, assuming that the input voltage in the primary winding 8decreases in value, the voltage of the rectified current across theterminals 25? and 21 of the coils 15 and 16 likewise decreases in value.This causes a decrease in saturation in the branch portions of the leg 4to permit an increase of A.C. flux through the leg 4. The increase inA.C. flux is directly in proportion to the decrease in voltage of theinput current across the terminals 9 and 1th of the primary winding 8.The increased A.C. flux through the leg 4 of the transformer willgenerate an increased voltage of the current induced in the A.C. coil30, which alternating current is fed through the rectifier 35 andadjustable reactor to supply a direct current to the coils 25 and 26which results in increased saturation in the leg 5 of the transformerwhich causes the flux in the legs 4 and 5 to stabilize and enable thewinding 11 to carry its full rated load without a shift or change offlux between the legs 4 and 5 of the transformer.

In case the voltage should increase across the terminals 9 and 10 of theprimary winding, the reverse procedure takes place with an increasedsaturation in the branch portions of the leg 4 because the voltageacross the terminals and 21 increases in value. Increased saturation inthe branch portions 15 and 16 of the leg 4 permits a decrease of A.C.flux through the leg 4. The decreased A.C. flux through the leg 4 willgenerate a current having a smaller voltage in the A.C. coil 30. Thiscurrent of decreased voltage is fed through the rectifier 35 to thecontrol coils and 26, thus decreasing saturation of the leg 5 so thatthe flux remains stable between the legs 4 and 5 to enable the secondarywinding to carry the rated load as set by the rheostat 36.

The apparatus as above described may be incorporated with a manuallyoperated rheostat to supply the direct current to the coils 17 and 18and coils Z5 and 26 in such a manner that they are varied so that theoutput current will go from Zero value to full value depending upon thesetting of the rheostat. By this means of control approximately 30 wattsof D.C. power can control, for example, 10,000 kva. of A.C. power, andhas application for voltage regulators and variable sources of voltage.

When used as a magnetic amplifier, it is possible to connect the devicefor use as a constant current transformer such as is used in seriesstreet lighting circuits, as illustrated in diagram in Fig. 3 of thedrawings. In this figure, 38 designates a street lighting circuit thatis supplied with current by means of the secondary 11 of thetransformer 1. 39 designates a conventional transformer that isconnected in the load circuit. The primary winding 40 of the transformer39 is connected in the lighting circuit and the secondary winding 41 isconnected with the coils 17 and 18 of the transformer as previouslydescribed, with a rectifier 42 being connected in the circuit. When theload current increases, the voltage output of the transformer 39likewise increases in value and the increased A.C. voltage is rectifiedand applied as a direct current in the control coils 17 and 18 on thebranches of the leg 4 of the core of the transformer 1. This increasesthe saturation of the leg 4 and decreases the A.C. flux therethrough,thus reducing the induced current in the primary 11 so that the outputvoltage is maintained substantially constant. The principle of using thereduced A.C. flux in the coils 17 and 18, which is the source of supplyfor the coils 25 and 26 on the branches of the leg 7 5 whereby the A.C.flux is divided and stabilized between the legs 4 and 5, remains thesame, so that a variable output voltage may be maintained which willrange at a straight line relation over considerable range of variableimpedance within the load connected to the trans former 39.

In the form shown in Fig. 5, the invention is shown in association witha conventional transformer 43 having spaced apart legs 44, 45 and 46 forcarrying a primary winding 47, a secondary winding 48 and a secondarywinding 49, respectively. The primary winding 48 may be supplied with analternating current from any suitable source for inducing secondarycurrents in the windings 48 and 49 for respectively applying a directcurrent to the coils 17-18 and 25-26, the windings 48 and 49 beingconnected in series with dry plate rectifiers 50 and 51 which have avery low resistance in the forward direction of the rectifier and a veryhigh resistance in the reverse direction of the rectifier. By connectingthe polarity of each rectifier with the windings, as shown in thediagram, there appears across the rectifier a voltage corresponding toeach half cycle depending upon the phase relationship of the windings 48and 49. By this method it is possible to use dry plate rectifiers ofvery small capacity for a source to feed direct current to the coils onthe branches of the legs 4 and 5 of the core 2 and have direct currentsof relatively large magnitude, for example, it is possible to use arectifier which has a capacity of only 400 or 500 milliamperes andconnect them to the transformer unit and have a D.C. output of 50amperes.

From the foregoing it is obvious that I have provided an apparatus forproducing a constant output current or an output current having avariable or constant-variable voltage. It is also obvious that thefeatures of the invention may be incorporated in a magnetic amplifierfor producing greatly amplified currents.

What I claim and desire to secure by Letters Patent is:

1. An apparatus for transforming an alternatin current having afluctuating voltage to an alternating current of different value and ofuniform voltage, including a core having three spaced apart parallel legportions interconnected at their opposite ends by bar portions toprovide closed paths for the magnetic forces produced in said core, aprimary winding on one leg of the core and having terminals adapted tobe connected with the alternating current supply of fluctuating voltage,a main secondary winding on another of the legs of the core in which thealternating current of different voltage value is generated responsiveto the induction of the current flow in the primary winding, said leg ofthe core having the main secondary winding and the remainin leg of thecore having divided portions, a winding on each of the divided portionsof the leg carrying the main secondary winding and having oppositepolarity whereby induced alternating current has no influence on theflux in said core, a circuit connecting the current supply of theprimary winding to the pair of windings, a current rectifier in thelast-named circuit whereby a variable direct current is supplied to thepair of windings for inducing magnetism in said core, windings on thedivided portions of the remaining leg of the core and having oppositepolarity, a smaller secondary windin on one of the divided portions ofthe leg carrying the main secondary winding to provide an alternatingcurrent induced by the current flow through the primary winding, acircuit connecting the smaller secondary winding with the windings onthe divided portions of said remaining leg, means in said last-namedcircuit for rectifying the secondary alternating current supplied by thesmaller secondary winding for producing a magnetic force in said core ofinverse 6 intensity to the magnetic force produced by the windings 0nthe leg carrying the main secondary winding for maintaining a desiredresultant magnetism in the core to establish a uniform voltage of thesecondary current generated in the main secondary winding.

2. An apparatus for transforming an alternatin current having afluctuating voltage to an alternating current of different voltage andof uniform value as described in claim 1, and means in the circuits forsupplying current to said windings of opposite polarity to control thevoltages of direct currents supplied to said windings.

References Cited in the file of this patent UNITED STATES PATENTS2,215,822 OHagan Sept. 24, 1940 2,245,192 Gugel June 10, 1941 2,339,406Holden Jan. 18, 1944 2,598,617 Stimler Nov. 17, 1948

